Video games currently on the market utilize various forms of potentiometric devices having control knobs, handwheels, levers, "joy sticks" or other manual input devices for performing the function of entering information, typically position information, into a video game chip. These typically require a grasping movement or action on the part of the users and a period of adjustment until the users have acclimated themselves to the required movements of the control instrumentality. There are, however, inherent limitations in the amount of excitement that can be generated by the use of such devices and the novelty of such games quickly wears off. Moreover, these devices do not admit of providing the user or each player with a replica of the playing field since the potentiometric device requires movement between two parts and a maintenance of a fixed relation between the two and hence does not have freedom of action over the "playing surface".
In my above-identified application Ser. No. 759,931, I disclose a human-machine interface which comprises a surface having a predetermined length and a reference point thereon. Electrodes at the lateral edges of the field establish low-level electric fields above the surface and along the predetermined length. The human finger is inserted in the field to touch a selected point on the surface and traverse a path therealong. The electric field, having a parameter that varies continuously along the predetermined length as a function of distance from a reference point, couples a signal into the human finger where touched thereby. A second surface is located in such a way relative to the first surface that when the user touches the first surface with his finger, an electrical signal is transmitted through the hand and coupled into the second surface. X and Y coordinates of excitation of the surface produce in the touching finger a component of the X oriented field, and a component of the Y oriented field as functions of the position of the detected finger where it touches the surface. A signal level detector is included for detecting the presence or absence of the operator's hand or finger at the "playing surface". These signals are converted into a utilization signal which is applied to a utilization device. In my application Ser. No. 867,256, filed Jan. 5, 1978, I disclose preferred linearization systems, and the use of a pressure sensitive device for translating touch pressure to a further control signal which is also applied to the utilization device.
The present invention is directed particularly to the incorporation of the human-machine interface disclosed in my above-identified applications into video games. The control surface when used as an input for video games is, preferably but not necessarily, a scaled linear model of the playing area. Touching it causes the paddle or other game feature to appear at the corresponding place on a video screen and takes the place of the standard potentiometers or other graspable implements used for communicating a player's action to the game. The size of the control surface can be made to accommodate any degree of scale reduction or enlargement of the playing surface disclosed in the video portion of the game. However, there are two sizes which seem natural and easily adapted for any use: a small size corresponding to the span of the forefinger with the heel of the hand resting on a support, which may constitute the second surface or input surface for the game and a larger, less clearly defined size for free movement of the entire hand where the second surface may be constituted by a ring or frame around the control surface. Preferences vary depending on physiological factors as small muscle control versus large muscle control or personality characteristics such as expansiveness versus preciseness. Pressure of the touching finger can be used as a further control signal.
One of the key problems of present-day controls or input instrumentalities for video games is the reliability of the controls themselves. Knobs come off, potentiometers fail, linkages bend, and levers break and this is particularly acute for arcade games which are plagued by vandalism and violet misuse. Efforts to alleviate these problems, such as incorporating clutches in the potentiometers, help somewhat, but the difficulties persist. The present invention therefore completely solves the mechanical reliability problem. Not only does it have no moving parts such as linkages, it has no projections at all and the control surface uses tough, durable, resistive materials developed for long life potentiometers. The failure mode limitations thus are those for ordinary solid state electronics.
The control surfaces can all be coplanar or, preferably, the pick-up surface can be above the control surface in a common housing.
The basic principle of operation consists of establishing an electric field over the control surface which electric field has a phase (or some other electrical parameter) varying as a function of position. When the user or player touches the surface, the signal at that point is capacitively coupled by his hand to the second and adjacent pick-up surface and the phase information is extracted from the signal. Time multiplexing utilizing the same circuitry gives output for both the X and Y axis. In addition to the foregoing, the presence or absence of the finger on the control surface can be used as a further input signal, and for this purpose a level detector connected to the output of the pick-up surface can be used to produce a binary signal to indicate the presence or absence of the finger on the control surface. Moreover, a pressure sensitive transducer may easily be combined with the control surface to introduce a further dimension to the game. Although the control surface and the pick-up surfaces are separately fabricated, they can both be produced from the same material if the impedance of the pick-up is small relative to the input impedance of the detection circuitry.